3
Troubleshooting
(continued)
Service Manual
45
Combustion Analysis Procedure
1. Turn the main power off to the boiler.
2. Remove the flue temperature sensor from the flue pipe
connection.
Note:
Combustion measurements will be
made at this point.
3. Turn the main power on to the boiler.
4. Place the boiler into the active position by pressing the
RIGHT SELECT [ON] key (see page 7).
5. Locate the pinhole button below the RESET button on
the display board (see page 7). Insert a thin wire (such as
a paper clip) into the hole and press the button once and
hold for 5 seconds to place the boiler into Service Mode.
In Service Mode the boiler will fire at ignition speed and
will then modulate up to full fire.
6. Insert the probe from a combustion analyzer into the
hole left by the removal of the flue temperature sensor.
7. Once the boiler has modulated up to full fire, measure
the combustion. The values should be in the range listed
in Table 3-6 above. The CO levels should be less than
150 ppm for a properly installed unit.
If the combustion is not within the specified range,
reference the chart below for possible causes and
corrective actions.
Table 3-5 Troubleshooting Chart - Combustion Levels
POSSIBLE CAUSE
CORRECTIVE ACTION
Vent/Air Intake Length
or Obstruction
• Refer to Section 3 - General Venting of the Knight Wall Mount Installation and Operation
Manual for the proper venting and air intake methods for the Knight wall mount boiler.
• Check for obstructions at the vent/air intake terminals.
Gas Supply Pressure
• Refer to Section 7 - Gas Connections of the Knight Wall Mount Installation and Operation
Manual for the proper gas supply for the Knight wall mount boiler.
Dirty/Damaged Burner
• Refer to page 31 of this manual for burner removal and cleaning procedures.
• Replace burner if necessary.
Gas Valve Adjustment
• Refer to page 46 of this manual for the gas valve adjustment procedure.
Table 3-6 Flue Products
Natural Gas
Propane
CO
2
O
2
CO
2
O
2
8.0% - 10%
3.0% - 6.5%
10.0% - 11%
4.1% - 5.4%
8. Once the combustion analysis is complete, test the safety
shutoff device by turning the manual shutoff switch to
the OFF position and ensuring that the boiler shuts
down and registers an alarm. Turn the manual shutoff
switch to the ON position, reset the control, and return
to Service Mode.
9. Turn the main power off to the boiler and replace the flue
temperature sensor into the flue pipe connection.
10. Place the boiler back into normal operation.
You must replace the flue gas temperature
sensor to prevent flue gas spillage into the
room. Failure to comply could result in
severe personal injury, death, or substantial
property damage.
WARNING
Summary of Contents for WH 399
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